A new psychological treatment for depression is under investigation. Patients are given a psychological test before and after treatment in order to determine the effectiveness of the treatment. Researchers hope to find a difference in test scores before and after treatment. A
95%
CI for the population average difference in test scores (before-after) is given by
(0.25,3.75)
, which was computed based on a random sample of 36 patients. a) What is the population parameter of interest?
\mu _(1) ? \mu _(2) ? \mu _(d) ?
b) Based on the confidence interval, at a
5%
significance level, would 0 be considered a reasonable value of the population parameter? c) Based on the CI , what is the value of the sample statistic (point estimate)? d) Based on the CI and the sample statistics found in c). What is the value of the standard error (SE) of the sample statistic? Hint:
UB=
point estimate + margin of error
()/(b)=ar (x_(d))+E()/(b)=ar (x_(d))+cv\times SE(/bar (x_(d)))
e) Is there a significant difference in test scores (before - after) on average? Perform an appropriate hypothesis test using
\alpha =0.10
. I. List data assumptions. II. State
H_(0)
and
H_(a)
. III. Calculate the test statistic. IV. Make decision using the rejection region approach. V. Draw conclusion.